Red Bull's Sebastian Vettel claimed his sixth pole position of the season to take a huge step towards his third drivers' championship.
The German leads Ferrari's Fernando Alonso by 10 points heading into tomorrow's race and victory would all but seal the title.
Alonso could only manage a ninth-place finish, but will start in eighth by virtue of Romain Grosjean's five-place grid penalty.
You can read how the action unfolded below.
Good evening Formula 1 fans and welcome to Sports Mole's live coverage of a pivotal qualifying session in Texas.
A slew of American celebrities and sports stars past and present are in tow for today's racing at the brand new Circuit of the Americas. Among the VIPs enjoying a pit-lane view is Hollywood director Ron Howard and former runner Michael Johnson. Former Friends star Matt le Blanc also looks like he's having a good time.
Vettel has dominated in practice. You just feel that all Alonso can do is keep the championship alive until next week and see what he can do in Brazil. Vettel had a sluggish start to the year, but has kicked into gear right when he's needed to.
McLaren boss Martin Whitmarsh has already voiced concerns regarding tyres. It takes time for them to warm up on this new track.
Qualifying is now underway and Kimi Raikkonen is the man who starts us off.
The Finn posts the early time of 1.41 to go ahead of Glock, Pic, Karthikeyan and De la Rosa.
Vettel is ready to come out of the garage.
Grosjean is the first man to break 1.40.
Here comes Alonso...
An average first sector for the Spaniard. He's eight tenths behind Grosjean's time.
Massa goes second, with Alonso third. The tyres are warming up, though.
We have just over eight minutes left and Grosjean still leads, ahead of Webber, Hulkenberg, Massa, Alonso and Button.
Hamilton was struggling in the drop zone but has posted the ninth-fastest time. Kovalainen, De la Rosa, Karthikeyan, Petrov, Rosberg, Schumacher and Kobayashi are also down there.
Vettel goes fastest with 1.37. Grosjean is second, followed by Massa, Hulkenberg, Webber, Senna, Button, Alonso.
Schumacher posts 1.38 at the first time of asking. He's into 12th now.
Karthikeyan comes to a standstill. He's 23rd anyway, and was likely to miss the cut.
Final two minutes of qualifying. Hamilton goes top, with Vettel in second. Rosberg, Glock, Pic, Petrov, Kovalainen and De la Rosa are in the drop zone. There is a yellow flag out for Karthikeyan's car, to make things worse for them.
Rosberg creeps into 17th and into the next session! Ricciardo is the man who drops out.
Ricciardo, Glock, Pic, Petrov, Kovalainen, De la Rosa, Karthikeyan
Vettel clocked the fastest time of 1.36.
Q2 is now underway.
Raikkonen posts 1.37. Senna is second, with Grosjean third.
Vettel, Webber, Kobayashi and Perez are yet to get out onto the track for Q2.
Hamilton goes first with a time of 1.36.
Alonso is just in, while Vettel is just out. Expect that to change shortly...
Five minutes left and Alonso is down into 12th. Meanwhile, Vettel smashes Hamilton's time by nearly one second to go top. Brilliant driving.
Christian Horner was delighted with that lap from Vettel.
Just over three minutes left and Senna, Grosjean, Vergne, Kobayashi, Rosberg, Perez and Schumacher are in the knockout zone.
Alonso goes fourth. That will see him into Q3 safely.
Button comes into the pit for a minor repair, but he'll need to get back out there as he is in a precarious position in 10th. On the cusp...
There's an electrical failure on Button's car and he's out!
Vettel and Webber have gone fastest. Hamilton is in third.
Senna just misses out on a place in the top 10! But he's also out along with Button.
Senna, Button, Di Resta, Vergne, Perez, Kobayashi, Rosberg
Vettel, Webber, Massa, Hamilton, Grosjean, Maldonado, Hulkenberg, Schumacher, Alonso, Raikkonen
Jenson Button: "It's a problem with the throttle. There's no power. Hopefully it's something we can get sorted for next year."
Button hasn't been very impressed with the McLaren machine this year. It has let him down on a few occasions, as it has with Hamilton.
Schumacher is first out of the traps in Q3.
Grosjean is currently the fastest man on the track, but with 1.36. Vettel went 1.35 in Q2 so don't expect that time to hold up.
And there goes Webber, taking top spot with 1.36. Red Bulls have so much pace around this circuit.
Hamilton now snatches provisional pole.
Vettel looks like he's about to usurp him. Quick first two sectors...
And there you go, Vettel takes pole with 1.35. That'll take some beating.
Alonso is down in 7th and needs to get something close to Vettel and Hamilton.
Hulkenberg goes 6th, pushing Alonso further down. Hamilton consolidates second with a time just a couple of hundreths slower than Vettel. Great pace!
Alonso can only manage 7th!
Vettel improves his time but Hamilton looks quick....
He just misses out by a tenth of a second! So very close from Hamilton! Superb driving!
Romain Grosjean has a five-place grid penalty so that should give Alonso an extra place, but he was bumped down to 9th and has a mountain to climb...
Vettel, Hamilton, Webber, Raikkonen, Schumacher, Massa, Hulkenberg, Alonso, Grosjean, Maldonado, Senna, Button, Di Resta, Vergne, Perez, Kobayashi, Rosberg, Ricciardo, Glock, Pic, Petrov, Kovalainen, De la Rosa, Karthikeyan
